JP2003106146A - Flow passage split type exhaust pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow passage split type exhaust pipe which eliminates pipe cracks through frozen bending. SOLUTION: In a pipe body 10, tip ends 1A and 1D of a plate-state body 1 connecting to a first bent part 1A and a second bent part 1B are wound respectively in the shape of a half arc surrounding a bulkhead part 3 to form a cylindrical shape, and each of the tip ends of the plate-state body 1 wraps around outer circumferential faces 10A and 10B of the pipe body 10, each of tip ends 1F and 1G of the wrap parts 1D and 1E is formed respectively through joining by TIG welding or laser welding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow channel split type exhaust pipe used for a multi-cylinder engine or the like, and more particularly to a pipe pipe cracked by freezing bending.

[0002]

2. Description of the Related Art Conventionally, as a pipe for circulating exhaust gas from a multi-cylinder engine to a muffler, a flow channel split type exhaust pipe in which a partition wall is provided inside an exhaust pipe to form two exhaust gas flow channels. It is provided. As an example, JP-A-9-
There is an exhaust pipe of 323119 gazette. This one is
As shown in FIG. 0, a plate-shaped body extending in the longitudinal direction is wound in the width direction, a partition plate is arranged in the pipe, and a plurality of flow paths are provided in parallel. The exhaust pipe 1 includes a partition plate 1a, a semicircular first side plate 1b for forming the first flow path a on one side across the partition plate 1a, and a second flow path roll on the other side. It has a semicircular second side plate 1c for forming the.
Then, the tip surface 1d of the first side plate 1b and the second side plate 1
The front end face 1e of c is brought into contact with the bent base portions 1f and 1g of the partition plate 1a and joined at the welded portions W and W.

However, when performing TIG welding or laser welding on the above-mentioned welded portions W, W, since the welded portion is located at the bent base portion of the partition plate, it is necessary to back shield from both insides thereof. Back shield is difficult to implement. For this reason, the structure changes due to oxidation during welding, and when performing the bending process of the above-mentioned pipe, the ductility of the welded part at low temperature decreases if the freezing bending process is performed by freezing the water contained in the pipe. There is a problem that cracks occur in the welded part due to (low temperature brittleness).

Further, as another example, Japanese Patent Laid-Open No. 2000-17
A flow channel split type exhaust pipe and a method for manufacturing the exhaust pipe as disclosed in Japanese Patent No. 0532 have been proposed. As shown in FIG. 9, this is a channel-division type exhaust pipe formed by winding a plate-shaped body extending in the longitudinal direction in the width direction thereof, and having a cylindrical pipe main body and the pipe. A partition part dividing a flow path in the main body part, wherein the partition part is a first bent part in which the plate-like body is bent in the vicinity of one end part in the width direction thereof;
The flat body portion is defined between the bent portion and a second bent portion that is bent at a predetermined distance, and the pipe main body portion has the remaining portion of the plate-shaped body following the second bent portion, It is formed by being wound so as to surround the partition wall portion, the one end portion of the plate-shaped body is wrapped around the inner peripheral surface of the pipe body portion, and the other end portion of the plate-shaped body is formed of the pipe body portion. It is formed by wrapping around the outer peripheral surface and joining the lap portions.

The flow channel split type exhaust pipe is composed of a pipe body 1
One end 2A of the plate-like body 2 wraps around the inner peripheral surface 1A of
The other end 2B is wrapped around the outer peripheral surface 1B of the pipe body 1. Therefore, the welding of the one end 2A located on the inner peripheral surface 1A of the pipe body 1 is limited to spot welding or seam welding. In the case of such a structure, the pipe is bent by inserting a fine iron ball into the pipe and bending the pipe. However, the above bending method has a problem that the heat insulating material cannot be inserted into the gap between the outer pipe and the inner pipe. Further, since the iron ball is press-fitted into the pipe, the structure of the product is regulated, and since the iron ball is completely removed, there is a problem that the structure is limited and the design cannot be freely performed.

[0006]

SUMMARY OF THE INVENTION The present invention has been made based on the above problems, and an object of the present invention is to provide a flow channel split type exhaust pipe in which pipe cracking due to freezing bending is eliminated.

[0007]

In order to achieve the above-mentioned object, a flow passage division type exhaust pipe according to a first aspect of the present invention is formed by winding a plate-like body extending in the longitudinal direction in the width direction thereof. In the flow channel split type exhaust pipe, a cylindrical pipe main body portion, and a partition wall portion that divides the flow channel in the pipe main body portion,
The partition wall portion is formed by bending the plate-shaped body on one side in the width direction thereof, and bending the other side on the other side at a predetermined distance from the first bent portion. It is composed of a second bent portion and a flat surface portion formed between the two bent portions, and the pipe main body portion is provided on each tip side of the plate-like body following the first bent portion and the second bent portion. The portion is formed into a cylindrical shape by being wound in a semi-circular shape so as to surround the partition wall portion, and each tip end portion of the plate-like body is wrapped around the outer peripheral surface of the pipe main body portion, It is characterized in that the tip portions are formed by being joined by TIG welding or laser welding, respectively.

The flow-path-divided exhaust pipe according to a second aspect of the present invention is the flow-channel-divided exhaust pipe according to the first aspect, wherein the tip end of the wrap portion that wraps the outer peripheral surface of the pipe body is bent. It is characterized in that it is formed at a position displaced from the outer diameter portion of the arcuate portion.

[0009]

According to the flow channel split type exhaust pipe of the first aspect of the present invention, in the pipe main body, the portion on the front end side of the plate-like body following the first bent portion and the second bent portion, It is formed in a cylindrical shape by being wound in a semi-circular shape so as to surround the partition wall portion. Then, the tip end of each wrap portion of the plate-like body is wrapped around the outer peripheral surface of the pipe body, and the tip end portion of the lap portion is joined by TIG welding or laser welding to form a welded portion. Specifically, the TIG welding or laser welding is after-shielded in an atmosphere of argon gas in which the outside of the exhaust pipe is closed by a cover. Further, the tip of each wrap portion is located away from the first bent portion, the second bent portion, and the partition wall portion with respect to the inner side of the exhaust pipe, and the inner side, which is the back surface thereof, has a wide cavity. Therefore, measures are taken to back shield by injecting argon gas into the exhaust pipe to fill it and back shield it, or to keep the core metal in close contact with the back surface of the welding surface to eliminate air intrusion. As a result, oxidation of the welded portion is prevented, and welding can be performed without structural change.

However, the above-described flow passage-divided type exhaust pipe is welded by taking measures against oxidation during welding, and does not cause low temperature brittleness. Therefore, in freezing bending of the exhaust pipe, cracks in the pipe can be eliminated, and the quality such as appearance can be improved. Further, since it is not necessary to insert a fine iron ball into the pipe and bend it, the structure of the exhaust pipe has a wide margin, and a flexible design is possible.

According to a second aspect of the present invention, there is provided a flow passage split type exhaust pipe in which a tip portion of a wrap portion which wraps around an outer peripheral surface of a pipe main body portion is displaced from an outer diameter portion of an arcuate portion to be bent. Since it is formed in the above, the welded portion is arranged at a position where the extension is small in the bending process.

As a result, the welded portion of the pipe main body can be more reliably prevented from cracking at the time of freezing bending, in addition to the low temperature brittleness countermeasure against this welded portion, and the bending strain can be minimized. It is possible to provide a quality channel-division type exhaust pipe.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the flow channel split type exhaust pipe of the present invention will be described below with reference to FIGS. 1 is an external view of a flow channel split type exhaust pipe, FIG. 2 is a sectional view of the flow channel split type exhaust pipe, FIG. 3 is a manufacturing process diagram of the flow channel split type exhaust pipe, and FIGS. 4 and 5 are flow channel split type. The perspective view and sectional drawing of the welding method of an exhaust pipe are shown.

As shown in FIG. 1, the flow channel split type exhaust pipe 100 of the present invention is a pipe for flowing exhaust gas G from a multi-cylinder engine E to a silencer 5 via an exhaust pipe P. A partition wall 3 is provided inside the pipe body 10.
By providing the two flow paths A1 for passing exhaust gas,
A2 is formed.

As shown in FIGS. 2 and 3, the flow channel split type exhaust pipe 100 is formed by winding the plate-like body 1 into a substantially S-shape. The wound plate-shaped body 1 includes a cylindrical pipe main body 10 and flow paths A1 and A2 in the pipe main body 10.
And a partition wall portion 3 that divides the partition wall. The partition 3 is
First bent portion 1A in which one side of the plate-like body 1 is bent
And a second bent portion 1B, which is bent on the other side from the first bent portion at a predetermined distance K to the opposite side, and a flat surface portion 3C formed therebetween. The pipe body 1
0 is a cylindrical shape in which each tip side part of the plate-like body 1 following the first bent portion 1A and the second bent portion 1B is wound in a semi-circular shape so as to surround the partition wall portion 3. The outer peripheral surface 10A, 10B of the pipe body 10 near the outer position O1 which is the outer diameter portion of the bending work and the inner position O3 which is the inner diameter portion of the bending work is wrapped to form a lap portion 1D, 1E. Then, each tip portion 1 of the lap portions 1D and 1E
F and 1G form welds Y1 and Y2.

Next, the manufacturing process of the above-described flow channel split type exhaust pipe 100 will be described with reference to FIG. In the flow channel split type exhaust pipe 100, first, as shown in FIG. 3A, the plate-shaped body 1 extending in the longitudinal direction L is formed in the width direction by a press molding machine or the like as shown in FIG. 3B. It is wound around M to form a substantially S-shaped cylindrical shape. The rolled plate-shaped body 1 has a cylindrical pipe main body 10 and flow paths A1 and A2 in the pipe main body 10.
And a partition wall portion 3 that divides the partition wall. The partition wall 3
Is a first bent portion 1A in which the plate 1 is bent on one side in the width direction M, and the other side is bent to the opposite side with a predetermined distance K from the first bent portion. 2nd bent part 1B
And a flat portion 3C between the two. Then, as shown in FIG. 3 (c), the pipe main body portion 10 includes the lap portions 1D and 1E of the plate-shaped body 1 following the first bent portion 1A and the second bent portion 1B, and the tip thereof. Parts 1F and 1G
The outer peripheral surfaces 10A and 10B of the pipe body 10 are wrapped with appropriate dimensions.

Further, as shown in FIG. 3D, the tip portion 1 is
F and 1G, after TIG welding or laser welding, fill the argon gas into the sealed space closed by the cover C, including the welding surfaces of the outer peripheral surfaces 10A and 10B of the pipe body 10 and the welding rod B, and after shield. AS is applied. Further, the inside of the outer peripheral surfaces 10A and 10B is filled with argon gas by being blown into the inside, or the cored bar S is brought into close contact with the inner surface of the welded portion to provide a back shield BS. The tip portions 1F and 1G are provided with an after shield AS and a back shield BS, and have outer peripheral surfaces 10A and 10B.
And welded portions Y1 and Y2 are formed. Next, FIG.
As shown in (e), the pipe main body 10 has an outer position O that serves as an outer diameter portion when the water contained therein is frozen.
1 is greatly extended and bent.

A specific welding operation of the welded portions Y1 and Y2 is performed as shown in FIG. 4 or 5. In the TIG welding or laser welding method shown in FIG. 4, the welding surfaces of the outer peripheral surfaces 10A and 10B of the pipe body 10 and the welding rod B are
The sealed space closed by the cover C is filled with argon gas Ar, and after shield AS is performed. Further, the inside of the outer peripheral surfaces 10A and 10B is provided with a back shield BS filled with argon gas Ar to be filled therein.

The TIG welding or laser welding method shown in FIG. 5 is applied to the outer peripheral surfaces 10A and 10B of the pipe body 10.
After shield AS in which the welding surface and the welding rod B of No. 1 are filled with argon gas Ar in a closed space closed by a cover C.
Is applied. Further, a back shield BS in which a core metal S is brought into close contact with the inner surface of the welded portion is provided on the inner side of the outer peripheral surfaces 10A and 10B.

That is, in the welded portions Y1 and Y2, the tip end side portion of the plate-shaped body 1 has the outer peripheral surface 10 of the pipe body 10.
Since it is wrapped in A and 10B, the lap parts 1D and 1E
The tip end portions 1F and 1G are located away from the first bent portion 1A, the second bent portion 1B, and the partition wall portion 3 with respect to the inner side of the pipe body portion 10, and the inner side which is the back surface thereof is also a wide cavity. Has become. As a result, the argon gas Ar can be blown into the interior to fill it, or the core metal S can be adhered to the back surface of the welding surface to reliably prevent air from entering, and the welded portion is prevented from entering air during welding. There is no structural change due to oxidation. Therefore, in a state where the water contained in the pipe body 10 is frozen, the outer position O1 is greatly extended and bent, and the welded portion Y does not have low-temperature brittleness during freezing bending.
1, Y2 does not cause pipe cracking.

The flow channel split type exhaust pipe 100 of the present invention is manufactured by the manufacturing method as described above, and
The effect is demonstrated. In the flow channel split type exhaust pipe 100, the tip end side portion of the plate-shaped body 1 has an outer peripheral surface 10 of the pipe body 10.
The welded portions Y1 and Y2 are formed by wrapping with A and 10B, and joining the tip portions 1F and 1G of the lapped portions 1D and 1E by TIG welding or laser welding. The lap section 1
The welding of F and 1G is carried out by TIG welding or laser welding, afterfilling the aftershield blocked in the atmosphere of argon gas, and filling the inside with argon gas, or by contacting the core S with the back surface of the welding surface Eliminating intrusion. As a result, oxidation of the welded portions Y1 and Y2 is prevented, the structural change is eliminated, and the low temperature brittleness is eliminated. There is no crack in the weld.

Therefore, in the flow path split type exhaust pipe 100, the welded portions Y1 and Y2 are welded while preventing oxidation at the time of welding,
Since measures have been taken to prevent low-temperature brittleness during freeze bending, pipe cracks can be eliminated during freeze bending and the quality such as appearance can be improved. Also,
Since it is not necessary to put a fine iron ball in the pipe and bend it, it is possible to bend with an insulating material interposed between the outer pipe and the inner pipe, and it is only necessary to provide a hole for draining water. The product structure has a wide margin and can be freely designed.

Further, the flow channel split type exhaust pipe 100 of the present invention is provided.
Can be a second embodiment as shown in FIG. This embodiment is suitable when the bending radius of the pipe body 10 is sharp. Wrap portion 1D, 1E
Is extended to the middle flanks O2, O4 of the outer peripheral surfaces 10A, 10B of the pipe body 10 for wrapping.
Thus, in the bending process of the pipe body 10, the welded portions Y1 and Y2 are located at the outer position O1 which is an outer diameter portion having a large extension.
To the middle abdominal position O2, O4.

According to the second embodiment shown in FIG. 6, when the pipe body 10 is frozen and bent, the welded portion Y is formed.
1 and Y2 are middle-sided positions O2 and O4 with little extension displaced from the outer position O1 which is the outer diameter part with large extension in bending.
Is located in. That is, as shown in FIG. 6 (b), the bending radius R1 of the outer diameter portion 1H having a large extension in bending,
The bending radius R2 of the inner diameter portion 1I having a small shrinkage due to bending and the welded portion Y1 that hardly extends or contracts,
And the bending radius R3 of Y2. As a result, in the welded portions Y1 and Y2, in addition to the low temperature brittleness countermeasure for the welded portions, bending strain can be suppressed to the minimum, and cracking can be reliably prevented.

Further, according to the third embodiment shown in FIG. 7,
The pipe body portion 10 has a middle portion in the lateral direction M in which one end portion 1D of the plate-shaped body 1 to be wrapped is offset from an outer position O1 which is an outer diameter portion 1H for bending, on the outer peripheral surfaces 10A and 10B. It is arranged at a position reaching the position O2. The other tip 1E is located at a position O3 near the inner diameter portion 1I of the bending process.
Is located in.

According to the third embodiment shown in FIG. 7, the welded portion Y1 is formed when the pipe body 10 is frozen and bent.
Is arranged in a middle-belly position O2 with a small extension, which is deviated from the outer position O1 which is the outer diameter portion 1H with a large extension in bending. That is, as shown in FIG. 7 (b), a bending radius R1 of the outer diameter portion 1H having a large extension in bending, a bending radius R2 of the inner diameter portion 1I having a small shrinkage due to the bending, and welding that hardly extends or contracts. And the bending radius R3 of the part. As a result, in the welded portion Y1, in addition to the low temperature brittleness countermeasure for this welded portion, bending strain can be suppressed to the minimum, and the occurrence of cracks can be reliably prevented.

Further, the channel-division type exhaust pipe 100 of the present invention is used.
Is not limited to the above-described respective embodiments in which the bending direction matches the direction of the partition plate 3. As in the fourth embodiment shown in FIG. 8, bending may be performed in a direction orthogonal to the direction of the partition plate 3. When this bending process is performed, the bending process can be performed with a small force, and as shown in FIG. 8, the lap portions 1D and 1E of the plate-shaped body 1 have a first bent portion 1A and a second bent portion. 1B is lapped with a short dimension on the outer peripheral surface near the outer diameter portion close to 1B. As a result, in the welded portions Y1 and Y2, in addition to the low temperature brittleness countermeasure for the welded portions, bending strain can be suppressed to the minimum, and cracking can be reliably prevented.

In addition, the above-described channel-division type exhaust pipe 100 is
The bending is not limited to the above-mentioned two bending directions, and bending in any direction is possible.
It is needless to say that by forming the positions of 1 and Y2 at positions displaced from the outer diameter portion of the arcuate portion to be bent, it is possible to set a position with little extension in bending.

[0029]

As described above in detail, according to the flow channel split type exhaust pipe of the first aspect of the present invention, the tip end side of the plate-like body following the first bent portion and the second bent portion is provided. Part wraps around the outer circumference of the pipe body, and the tip of the wrap part
After-shielding of argon gas by welding or laser welding, and the inside of the exhaust pipe is filled with argon gas, or a back shield that adheres to the back of the welding surface with a core bar to prevent air from entering is provided and low-temperature brittleness measures are taken. Therefore, in the freezing bending process of the flow path split type exhaust pipe,
It is possible to obtain a flow path split type exhaust pipe of good quality with no pipe cracks in the welded portion. Also, because it is not necessary to insert a fine iron ball into the pipe and bend it, there is a margin in the structure of the exhaust pipe,
Free design is possible.

Further, according to the flow passage split type exhaust pipe of the second aspect, one end of the plate-like body that wraps around the outer peripheral surface of the pipe body is bent from the outer diameter portion of the arc-shaped portion. Since it is formed at a shifted position, the welded part can be placed at a position with little extension that deviates from the outer diameter part of the bending work, and the welded part of the pipe body is a low temperature brittleness countermeasure against this welded part during freeze bending In addition, bending strain can be suppressed to a minimum, and cracking can be prevented more reliably.

[Brief description of drawings]

FIG. 1 is an external view of a flow channel split type exhaust pipe of the present invention.

FIG. 2 is a cross-sectional view of the flow channel split type exhaust pipe of the present invention.

FIG. 3 is a manufacturing process diagram of the flow channel split type exhaust pipe of the present invention.

FIG. 4 is a perspective view showing welding of the flow channel split type exhaust pipe of the present invention.

FIG. 5 is a cross-sectional view showing welding of the flow channel split type exhaust pipe of the present invention.

FIG. 6 shows a second embodiment of the present invention, and is a cross-sectional view and a side view of a bending process of a flow channel split type exhaust pipe.

FIG. 7 shows a third embodiment of the present invention, and is a cross-sectional view and a side view of a bending process of a flow channel split type exhaust pipe.

FIG. 8 shows a fourth embodiment of the present invention, and is a cross-sectional view and a side view of bending of a flow channel split type exhaust pipe.

FIG. 9 is a cross-sectional view of a flow channel split type exhaust pipe of a conventional example.

FIG. 10 is a cross-sectional view of a flow channel split type exhaust pipe of a conventional example.

[Explanation of symbols]

1 plate 1A 1st bending part 1B 2nd bending part 1D, 1E lap part 1F, 1G tip 1H outer diameter part 1I inner diameter 3 partitions 3C flat part 5 silencer 10 Pipe body 10A, 10B outer peripheral surface 100 split channel exhaust pipe A1, A2 exhaust gas flow path AS After Shield Ar Argon gas B welding rod BS back shield C cover L longitudinal direction K predetermined interval M width direction O1 outside position Near the inside of O3 O2, O4 Middle position Bending radius of R1 outer diameter part R2 Bending radius of inner diameter R3 Weld radius S core Y1, Y2 weld

Claims (2)

[Claims] 1. A flow passage-dividing exhaust pipe formed by winding a plate-like body extending in the longitudinal direction in the width direction thereof, wherein a cylindrical pipe main body and a flow passage in the pipe main body are divided. A partition part, wherein the partition part has a first bent part in which the plate-like body is bent on one side in a width direction thereof, and the other part is spaced apart from the first bent part by a predetermined distance. And a second bent portion bent to the opposite side, and a flat surface portion formed between the second bent portion and the second bent portion, and the pipe main body portion includes the first bent portion and the second bent portion.
Each tip side portion of the plate-like body following the bent portion is wound in a semi-circular shape so as to surround the partition wall portion and formed into a cylindrical shape, and each tip-end portion of the plate-like body is formed as described above. A flow-path-divided exhaust pipe, which is formed by wrapping on an outer peripheral surface of a pipe main body, and by forming the tip end of each wrapping portion by TIG welding or laser welding. 2. The pipe according to claim 1, wherein a tip portion of the wrap portion that wraps the outer peripheral surface of the pipe main body portion is formed at a position displaced from an outer diameter portion of an arcuate portion to be bent. Flow path split type exhaust pipe.